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A male who has reached puberty will produce millions of sperm cells every day in the testicles. It takes âsperm about 4 to 6 weeks to travel through the epididymis into the Vas Deferans. The seminal vesicles âand prostate gland produce secretions which mixes with sperm to form semen. Each time a guy âejaculates, it can contain up to 500 million sperm.â
When the male ejaculates during intercourse, semen is deposited into the female's vagina. From the âvagina the sperm make their way up through the cervix and move through the uterus with help from âuterine contractions. If a mature egg is in one of the female's fallopian tubes, a single sperm may âpenetrate it, and fertilization, or conception, occurs.â
Hence you need not bother if the sperm is fresh or not. Only healthy and highly motile sperms are able to travel from the vagina to the fallopian tube where fertilisation of the egg occurs.
All the older sperms (so to say) just add to the numbers.
I hope this helps.